Embodiments of the invention are directed, in general, to communication systems and, more specifically, methods of reducing medium contamination.
Next-generation mobile devices will be able to access a variety of network technologies including, for example, worldwide interoperability for microwave access (WiMAX) networks, wireless local area network (WLAN) networks, long term evolution (LTE) mobile telephony networks, personal area networks (PANs), wireless universal serial bus (USB) networks or BLUETOOTH® (BT) technology networks, etc. The various applications have different transmission timing requirements in order to provide a needed quality of service (QoS). Quality of service refers to mechanisms for controlling resource reservation rather than the achieved service quality. QoS is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow, e.g., guarantee a required bit rate, delay, jitter, packet dropping probably, bit error rate, etc. Quality of service guarantees are important, for example, if the network capacity is insufficient or limited, especially for real-time streaming multimedia applications such as voice over IP, online games and IP-TV, since these delay sensitive applications often require fixed bit rate.
The IEEE802.11 specification provides a quality of service control protocol that enables a service differentiation to be provided for packets. For example, voice and e-mail traffic require different quality of service levels to provide acceptable service quality. In particular, voice packets need to be delivered within strict delay bounds whereas e-mail packets are more delay tolerant.
While increased access to these technologies will benefit users and operators alike, interference among different technologies, particularly onboard a single device, introduces difficulties during concurrent operation of these technologies. For example, and as illustrated in FIG. 1, wireless local area network (“WLAN”; 2.4-2.5 GHz) and other technologies, such as Bluetooth (“BT”;2.4-2.4835 GHz) and Worldwide Interoperability for Microwave Access (“WiMAX”;2.3-2.4 GHz and 2.5-2.7 GHz), operate at relatively close and, in some cases, overlapping frequency bands with respect to each other—so close, in fact, that the out-of-band emission by either technology may saturate the receiver of the other technology resulting in potential blocking. Therefore, the interference between these two technologies operating in the same device creates challenges on the coexistence of the corresponding wireless interfaces of that device.
To solve the coexistence problem, in which WLAN technology is one of the subsystems operating in the same device, time multiplexed operation have been proposed if both subsystems share the same antenna. For example, in the case of WLAN and BT coexistence, BT voice calls take priority over other traffic flows in WLAN. During the time periods that the device operates in BT mode, the WLAN operates in unscheduled automatic power saving delivery (U-APSD) mode. During the time that the device operates in WLAN mode, it sends a trigger frame (or a PS-Poll) to the AP indicating that it is ready to receive packets. To protect the network from the avalanche effect (caused by rate fallback mechanism due to the fact that the STA operating in BT can not send ACK packets to the AP, hence the AP reduces the transmission rate) the use of CTS-to-self has been proposed as a viable solution. Thus, before the STA transits to the BT mode, it sends the CTS-to-self frame and reserves the medium until the time that BT transmission ends and the gap/idle BT interval starts. If both subsystems share the same antenna as well as a low noise amplifier (LNA); then reception of packets in both subsystems is possible. Transmission however, is not allowed. Even though the subsystems can both receive, CTS2Self frame is sent to protect from the avalanche effect.
What is needed is a reduced NAV setting by CTS2Self frames by estimating packet received and data rate used to improved time optimization for sending of CTS2Self frames when receive/receive option is enabled for WLAN/BT subsystems.